Automatic stop mechanism for grinding machines or lathes



Aug. 3l, 1937.

J. D. SCAIFE ET AL 2,091,527

AUTOMATIC STOP MECHANISM FOR GRINDING MACHINES OR LATHES Filed Jan. 30, 1935 2 Sheets-Sheet l Fig. I.

Aug. 3l, 1937. J. D. SCAIFE ET AL AUTOMATIC STOP MECHANISM FOR GRINDING MACHINES OR LATHES Filed Jan. 50, 1935 2 Sheets-Sheet 2 Patented Aug. 31, 1937 UNITED STATES PATEN'q @FFME AUTOMATIC STOP MECHANISM FOR GRIND- ING MACHINES R LATHES Application January 30, 1935, Serial No. 4,202 In Great Britain June 1, 1934 3 Claims.

This invention relates to a type or class of apparatus or mechanism made use of to determine when the desired diameter of a bar of metal or the like, which is being ground in a grinding 51 machine or turned in a lathe, has been reached.

To attain this object it has already been proposed to use a detector lever having a certain part of its surface prepared by the mounting thereon of a diamond or similarly hard substance which will resist wear when in and by its Contact with the article being turned, While the other arm of the lever is extended from its p-ivot in order to actuate a pointer to travel over a dial or scale to indicate to the attendant the extent l5 to which the grinding or turning actions on the article being treated have been carried.

In such apparatus the indicator may be used by the attendant so that on reaching the desired marking on the dial he can, by manually operating lever mechanism, arrest the motion of the machine, and therefore the cutting or grinding actions. In other arrangements the indicating armof the lever has been made to operate an electric switch, so that,v by the current energizing an electro-magnet, the actions of same would also arrest the grinding or turning operations.

' When manually operated mechanism is employed, variations in the time of action cannot be accurately secured, while when switch mechanism wherein metallic or hard, rm surface contacts for completing the electric circuit are to be used, it is found to be impossible to produce intimacy in the fitting engagements of the two contacting surfaces to be at all times in exactly one and the same plane. Consequently the arresting actions of the grinding or cutting tool upon the article being treated have not been eiected with that precision and certainty that is required for producing articles of standard measurement requiring the closest trade accuracy.

In accordance With our present invention We make use of detector lever mechanism which is arranged to be operated as heretofore by the gradual reducing of the diameter of the article being produced, and this lever mechanism We mount upon its supporting members so that it may move under the action of a spring or of gravity with the precision required by reason of all back-lash in the operating members that are employed being entirely eliminated, While the controlling feature We employ comprises an intercepting member or shutter operated by the detector elements referred to, to cut-oli rays or a beam of light from acting upon a photo-electric cell or to cut-oli a similarly imponderable medium from controlling the actions of an electromagnet to stop or remove the grinding or turning actions under the completed conditions and With the results as stated.

We hereinafter describe our invention as applied to a grinding machine (a suiiicient portion of which machine is illustrated by the accompanying sheets of drawings to show the application thereto of our improved apparatus) from 10 which it will be understood, by those having a knowledge of machine tools,l how our said apparatus may be applied to a lathe.

Fig. l is a side sectional elevation showing certain parts of our improved apparatus in posi- 15 tions as and when in use.

Fig. 2 is a side elevation of other of our devices with one of the detachable side members removed Fig. 3 is a sectional plan of certain parts of apparatus hereinafter described. 0

Fig. 4 is a similar View to Figs. 1 and 2 but shows a modification in the formation and arrangement oi the detector lever and its co-operating members hereinafter explained.

Fig. 5 is a side elevation of the detector lever 25 and pointer which it operates, the enclosing member for the pointer being shown in section.

Fig. 6 is a sectional elevation of the casing or enclosing members Within which the shutter is mounted and Within which the photo-electric 30 cell and the electric lamp are situated. The said enclosing members are shown in section in order that the respective positions of the leads therein may be seen.

Fig. 7 is a diagram showing the arrangement 35 of the electro-connections and Where same may be joined' to the relays which supply current to the electro-magnet.

Fig. l is drawn to a larger scale than are the other gures. 4o

In the accompanying sheets of drawings, 2 indicates the article which is being acted upon by the grinding wheel or rotary grinding tool 3.

When in action the article 2 is supported between the ends of the rotary and fixed spindles 45 (not shown) oi theV grinding machine which is of any known regulation or character wherein driving gear is employed for imparting or transmitting rotary motion to its driving spindle and therefore to the article 2 in the usual and well known 50 manner.

The rotary grinding tool 3 is fixed upon its operating shaft 4 which is supported upon its usual form of bearings so that rotary motion may be transmitted to it to carry it in the direc- 55 tion indicated by the arrow b, while the rotary motion of the article 2 is carried out in the direction indicated by the arrow a. The rotary motion of the article 2, as well as that of the tool 3, is transmitted to each of them through clutch couplings of any desired type which will allow their engagements and disengagements to be quickly effected in order to arrest and to restart the rotary motions of said article 2 and tool 3 with precision.

The shaft 4 is mounted upon bearings which support it in the usual manner so that by cam, screw or other known mechanical actions, said bearings maybe operated to carry the tool 3 gradually into its actions upon the article 2 and quickly to withdraw said tool therefrom when its grinding actions have to cease as is hereinafter explained.

In the arrangement of our devices as shown by Figs. 1 and 2, the detector 5 is in the form of a lever which is pivoted at 5b to an extending arm 5a from our lamp and photo-electric-cell supporting and enclosing members 6.

This member 5 is pivoted upon a fulcrum pin "la which is fixed upon the bifurcated arms 'Ib of a bracket l, and this bracket 'I is xed upon a pillar S, the base of which is xed upon the framework 9 of the machine.

To the rear of the enclosing member 5 extends an arm 6b to which is attached the upper end of a spring l that reaches for its other end to be secured to the bracket l. This adjusting of the member 5 in the position stated enables said adjustment to bring and force the prepared hard surface 5a of the detector member 5 against the peripheral surface of the article 2 which is being acted upon by the grinding tool 3.

To enable the attendant readily to adjust the surface 5a relative to the diameter of the article 2 a screw lI with its lock-nut I Ia is made to take against the outer surface of the enclosing member 6 so that the advancing of the screw II is carried out against the retraction of the spring ill. The locking of the member E in its adjusted position may be carried out by rotating the screw 35 by its handle 36d and so gripping the arm 5b.

The pivoting of the detector lever 5 is effected by fixing said lever 5 to a flat spring I 2 which is fixed upon the arm 6a of the member 6, and said fixing of the member 5 to the spring I2 is effected by a plate I2a having a screw taking through it and through the spring I2 to be fixed into the projection 5b of the member 5. The other arm 5d of the member 5 is arranged for contact with the extending end I3 of a lever which is mounted on a pivotal spindle I 3a situated at the base of the member Upon the pivotal spindle I3a a pointer shaped shutter M (hereinafter referred to as a shutter) is made to reach vertically within the casing B so that by a retracting spring Illa, the lever arm I3 may have its outer end normally at all times kept in contact with the upper surface of the arm 5d of the member 5.

Normally at the commencement of the grinding operations of the tool 3 upon the article 2, the member 5 will occupy the position shown by Fig. l, and therefore will retain the shutter I4 in its rearward position, also shown by Fig. 1, and as the diminishing of the diameter of the article 2 proceeds, said shutter I4 will, by the receding of the arm 5d of the member 5, be caused to advance under the recoil of the spring Ida to approach a slot or narrow elongated opening Bd made through the wall of the member 6.

This approaching of the shutter I4 (which is at an increased speed relative to that of the movement of the surface 5a by reason of the surface 5d moving the short lever I3 to carry the shutter I4 through a greatly increased space)r will continue until its position shown in broken lines at Mw of Fig. 1 will cover the elongated slot 6d so as to intercept the beam or ray of light in the manner and for the purpose hereinafterdescribed.

Further, to increase the speed or quickness of action at which the beam of light is shut-off or intercepted, we form said slot 6d. of as large a length and as narrow a width as the cross sec'- tional area of the beam determines. By these means the covering movement of the shutter I4 to eect the interception stated is reduced to the lowest limit.

Additional adjustment of the arm 5d, relative to the member 6, is effected by means of the adjusting screw I5 as and when desired, while the movements of the member 5 and its arm 5d are limited by a further adjusting screw I 5a being xed upon a member II6 that is secured to the bracket 1.

By the arrangement of the springs I and Ida, and in addition to the spring I2, all back-lash or unnecessary movements of the shutter I 4 is or are prevented, since while the lever I3 is normally held against the upper surface of the arm d by the spring Ia, no movement of the shutter Ill can occur in the direction when it is moved by the spring I4a except that which is permitted by the actions of the surface of the lever I3 allowing its contact with that of the arm 5d. While further, the oscillations of the lever 5, under the bending actions of the spring I2 (which thus forms the fulcrum of said lever 5) also prevent all back-lash and secure the constant and limited motion of the member 5 as produced by the diminishing diameter of the article 2 throughout all the grinding operations.

The member 6 has at one side of it a further enclosing member I6 as shown by Figs. 3 and 6, and on the other side of it another enclosing member IBa. Within the enclosing member I6 is mounted a photo-electric cell Il, While within the enclosure Ia, is mounted an electric lamp I8.

The leads I9 and E9e for the electric current to be supplied to the. cell l I occupy the positions shown by Fig. 6, while the leads 20 and 20a to the lamp IS also occupy their respective positions shown by the same figure.

Through the wall of the enclosing member Ilia an elongated slot Iw is formed opposite a similar second slot 5w (Fig. 3) made through the wall of the member 6, in order that through these two slots or slits the rays of light from the lamp I8 may pass to travel forward through the space within the member 5 and beyond same. through the elongated slot 5d formed in the opposite wall of said member 6 in order that said rays may impinge upon the outer surface of the photoelectric cell I'I, when the shutter I4 is not in position to intercept them by covering the slot 6d as is hereinafter explained.

Vxhen the surface 5a of the member 5 has been allowed to approach the centre of rotation of the member 2 which is being ground to the position where the further grinding operations have to cease, the motions of the member 5 transmitted through the lever I3 will have brought the shutter over so as to cover the slot 6d, and therefore the ray of light from the lamp I8 to the cell Il will be shut-off, and at this time the circuit through said cell il will cease to transmit current to the desired series of amplifying valves arranged in a position to the rear of the space A shown by Fig. 7. Thus at this time the electromagnet 22 will cease to be energized so that the spring of the armature 23 will move said armature to complete a circuit through the magnet 24 which will operate its armature 2da to complete the circuit through an electromagnet 25, and this electromagnet is brought into use for actuating the clutch mechanism or like transmitting members to be disengaged. Consequently the grinding actions will be arrested, the grinding tool 3 and the article 2 will cease to rotate, and the grinding tool 3 may further be removed from contact with said article 2.

When the grinding actions have nished, the attendant will remove the article 2 in its iinished condition and will substitute another article. to be again treated by the grinding tool 3 which, on the attendant re-starting same into action, will automatically be adjusted ready to be advanced. by its feed mechanism to repeat the grinding operations until again the same are completed as is stated.

It will be observed that the surface 5a, according to the arrangements shown by Figs. 1 and 2, is a member which is actuated by a lever arm. However, according to the arrangement shown by Figs. 4 and 5, the member 5a may be fixed upon a member 5w which will rest by gravity upon the article 2 which is being ground as is shown by Figs. 4 and 5, and in this case, by they descent of the surface 5a, as the grinding operations progress so will the spring Ma actuate the shutter I4 which is operated by the lever I3 to carry out all the functions hereinbefore described by reference to the arrangement of devices shown. by the other gures. However, in making use of the devices as shown by Figs. 4 and 5 the surface 5a and its supporting members, together with the adjustable guiding extensions 26 and 26a., will. have to be removed from the positions shown byl Fig. 4 to enable or permit the attendant to remove the finished article and substitute an uniinished one for same, and in thus removing saidr members the supporting arm 5a is arranged tol be carried upon the lever devices 30, 3l and 32 which are pivoted at 33 so that they may be raised from the position shown in full lines Fig. 4- to the inoperative position shown in broken lines of the same gure.

We have found that the .arrangement of thedevices hereinbefore described, whereby a beam of light having a cross sectional area of an elongated shape is made to impinge upon a photoelectric cell, enables said beam to be. so quickly' intercepted that the actions of the apparatus may be used to light a lamp to indicate that the desired size of the article has been reached soA that the attendant may then stop the actionsy within certain limits oi' accuracy that may meet ordinary requirements.

Such being the nature and object of our invention, what we claim isz- 1. In mechanism for arresting the operations:

of a grinding machine or lathe. in combination, a detector device in the form of a lever, a at spring fulcrum device for supporting said lever, a spring for normally forcing the detector end of the lever against the surface of the article being treated, a shutter pivoted Within a casing to cover an elongated opening made through the wall of said casing, a lever fixed to said shutter, a spring to actuate the shutter and its lever, another casing mounted adjacent to the Wall of the casing containing the shutter, a photo-electric cell mounted within said casing, another casing mounted on the opposite wall of the casing within which the shutter is situated, an electric lamp mounted within said casing, electric connections from the photo-electric cell to a series of amplifying valves and electric connections from said amplifying valves to an electro-magnet for operating the stopping mechanism of the grinding tool.

2. In mechanism for arresting the operations of a grinding machine or lathe, a fixed support, a rockable member pivotally mounted thereon, a detector lever pivotally mounted on said member and having a contact element normally pressed against the work, spring means tending to rock said member in a direction to press said element against said work, an adjustable stop normally engaged by said member and held in engagement therewith by said spring means, a shutter pivotally mounted on said member, said shutter having a portion engaging said detector lever to rock the same and to be rocked thereby, .spring means attached to said shutter tending to rock the shutter and detector to press the contact element against the Work, and photoelectric apparatus operatively associated with said shutter to control stopping mechanism for 'the machine.

3. In mechanism for arresting operations of .grinding machines or lathes, a Xed support, a member pivotally mounted on said support, said member including a screen with a slit therein, va

detector lever pivotally mounted on said member .spring means normallytending to rock said second lever toward slit-covering position and thereby to rock the detector lever to press against the "work, and photo-electric control means including .a lamp and a photo-electric cell aligned on oppo- .site sides of said slit and cooperating with said .shutter to control stopping mechanism for the machine.

JOSEPH DYSON SCAIFE.

JOHN LUND. 

